Area selective atomic layer deposition (ALD) is a technique for depositing layers with a thickness of a predetermined number of atoms. Area selective atomic layer deposition (ALD) is described in an article by Xirong Jiang et al., titled “Area Selective ALD with Soft Lithographic Methods: Using Self-Assembled Monolayers to Direct Film Deposition”, published in the Journal of Phys. Chem. C 2009, 113, pages 17613-17625. Jiang et al describe a process wherein a self assembled monolayer (SAM) is applied to a substrate in a two dimensional pattern with a printing stamp. Subsequently, ALD is used to apply an atomic layer on the substrate. That is, a number of different gasses are successively fed to the substrate and removed, so that first atoms from the first gas attach to the substrate selectively where the SAM is absent and subsequently successive atoms from subsequent gasses attach to the atoms from the previous gas on the substrate where they are present. Gas components are used that attach only to the atoms from the previous gas, so that the thicknesses of the resulting layers each are no more than one atom. WO2009/061199 discloses a number of SAMs.
The ALD process takes considerable time, for applying each gas, waiting until the atoms from the gas have attached to the entire available surface, evacuating the gas and repeating with the next gas.
US2009/0081827 discloses an ALD process for forming a patterned thin film, wherein a deposition inhibitor material is applied to a substrate and patterned after or during deposition, so that selected areas of the substrate have do not have deposited inhibitor material. Subsequently an inorganic film material is deposited in the selected areas. The document describes that patterning can be done by any method known in the art, including photolithography using photo-resists, laser ablation etc. An example is described wherein of exposure for 5-15 minutes through a photomask and developing the exposed sample for 45-90 seconds in toluene, followed by rinsing. Another example uses a direct printing process using an elastomeric stamp with a patterned relief structure, which was held in contact with the substrate for 3 minutes. A further example involved inkjet printing after placing the substrate in the sample holder of an inkjet printer, followed by a 10 minute annealing step.
The pattern of inhibitor material is applied in preparation for the process of depositing the inorganic film. When the substrate is subsequently exposed to inorganic film material in a deposition apparatus, the inorganic film material attaches only to the areas without inhibitor. US2009/0081827 discloses that the substrate can be exposed to the inorganic film material by means of a floating delivery head that outputs a number of different gases via output channels facing the substrate. The gases include two species of reactive gas and an inert purge gas. The delivery head floats above the surface of the substrate, and the substrate and the floating head are moved relative to each other in a direction parallel to the surface of the substrate in a reciprocating way.
WO 2008/027125 discloses an integrated apparatus for performing substrate surface treatment and film deposition for copper interconnect. The apparatus comprises a chamber in which a plurality of proximity heads for dispensing treatment gas. An embodiment is described wherein the treatment gas is excited before it is dispensed. The document describes that the treatment gas can be excited by a hot filament, by UV, a laser or by a plasma.
In a co-pending, unpublished patent application No PCT/NL/2009/050511, assigned to the same assignee as the present patent application a device and method for applying gasses to a substrate has been described that apply a precursor gas using an injector head that hovers over a substrate by means of a gas bearing. This co-pending patent application No PCT/NL/2009/050511 is incorporated herein by reference.
Use of SAMs for photolithography has been discussed in an article by Hiroyuki Sugimura et al, titled “Photolithography based on organosilane self-assembled monolayer resist” and published in Electrochimica Acta 47, (2001) pages 103-107. Sugimura et al note that SAMs detach from a substrate under Vacuum Ultraviolet light. More generally, SAMs may detach under UV light or even under light at other wavelengths.